Re: Tuning RMAN backup and recovery
- From: "Greg Rahn" <greg@xxxxxxxxxxxxxxxxxx>
- To: don@xxxxxxxxx
- Date: Fri, 16 Nov 2007 00:47:45 -0800
What are the disk stats during the backups (from iostat)? Some things
I would investigate:
- are the target drives saturated?
- are the I/O channels saturated?
- do /rman and the db file luns share physical spindles? (hopefully not)
I would suggest that you should have N luns where N is the number of
parallel streams. This allows N I/O SCSI queues to be simultaneously
serviced vs. one. Think of this like more check out lanes at the
grocery store.
Compression has the CPU overhead, but reduces the IO bandwidth and
storage space requirement. If you are not I/O bound (or space) then
it won't provide any visible performance gains - it will just consume
more CPU. It's basically a trade off.
Ultimately you want the target writes to be the bottleneck, but
operating at optimal efficiency.
On 11/15/07, Don Seiler <don@xxxxxxxxx> wrote:
> Some quick answers to these questions before I hop into bed.
--
Regards,
Greg Rahn
http://structureddata.org
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